I had a kernel panic about 2 years ago, and another one a few days ago. I haven't had any other problems besides minor software bugs, and I was able to harmlessly reboot after both. I've been told this can mean many bad hardware-related things. Could it just be something relatively harmless, since it doesn't really seem too persistent? Is it worth having it checked out?

Twice in as many years isn't something I'd consider worrisome; twice in, say, an hour - that's different. That said, it's always a good reminder to make sure that your important data is backed up and known retrievable (regularly test restoring from your backup solution); to run Software Update and install any available patches and upgrades; and to run a maintenance utility, such as the always-excellent Cocktail or MLCC.
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da4Dec 7 '12 at 21:35

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I agree. Not something to worry about. Non-ECC RAM can have random single bit errors that would cause the odd kernel panic. It happens, nothing to do or worry about really. If it starts happening frequently or at least with some regularity, then start worrying, but at the moment, I wouldn't sweat it. As da4 says, it's a good time to check your backups.
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robmathersDec 7 '12 at 21:50

Yes, sometimes a kernel panic can indicate bad/damaged or incompatible hardware. The frequency with which you have them is probably not indicative of a major hardware problem (i.e. bad cable connected to MotherBoard from HDD, etc.), unless you notice physical conditions that seem to coincide (i.e. hottest day of the year, child pounding on desk, etc.), or while performing the same software related task (i.e. clearing caches). It could be as simple as having one system file corrupted that is not often used.

On the other hand, I have also seen this caused by having hardware just lose its connection slightly (i.e. an eSata ExpressCard slipping out just a little while in use on a 17-inch MacBook Pro).

Twice in two years is nothing. Computers run on electrical signals not 0 and 1. Yes, sometimes errors occur. 'Single-bit errors' may occur, but the hardware and your OS are smart enough to deal with them most of the time. However, sometimes, they can't and you get the kernel panic, indication of something serious went wrong, perhaps not possible to correct. Twice in 2 years doesn't necessarily mean faulty hardware, just random unlikely errors.

If you are so worried about, you can start inspecting your hardware. Most kernel panics I have encountered were due to bad RAM modules! Start by running a memory test and see what you get.